Tjomme van der Bruggen

Inhibition of Human Immunodeficiency Virus Type 1 Replication in Human Mononuclear Blood Cells by the Iron Chelators Deferoxamine, Deferiprone, and Bleomycin

Replication of human immunodeficiency virus type 1 (HIV-1) can be influenced by iron. Hence, decreasing the availability of iron may inhibit HIV-1 replication. Deferoxamine and deferiprone, both forming catalytically inactive iron-chelator complexes, and bleomycin, by use of which iron catalyzes oxidative nucleic acid destruction, were investigated. Expression of p24 antigen in human monocyte-derived macrophages and peripheral blood lymphocytes (PBL) was reduced by all 3 iron chelators. In PBL, p24 reduction was mirrored by a decrease in proliferation after incubation with deferoxamine or deferiprone, suggesting that viral inhibition is closely linked to a decrease in cellular proliferation. In contrast, clinically relevant bleomycin concentrations reduced p24 levels by approximately 50% without affecting proliferation. When deferoxamine and the nucleoside analogue dideoxyinosine were used in combination, they acted synergistically in inhibiting HIV-1 replication. These observations suggest that iron chelators with different mechanisms of action could be of additional benefit in antiretroviral combination therapy.

Bacteremic Complications of Intravascular Catheters Colonized with Staphylococcus aureus

Patients with Staphylococcus aureus colonization of an intravascular catheter but without demonstrated bacteremia within 24 h after intravascular catheter removal had a 24% (12 of 49 patients) chance of subsequent S. aureus bacteremia if they did not receive immediate antistaphylococcal antibiotics. Treatment within 24 h after intravascular catheter removal led to a 83% reduction in the incidence of subsequent bacteremia.

Effect of corticosteroids on nuclear factor-κB activation and hemodynamics in late septic shock

ObjectiveTo describe the underlying pathophysiologic mechanisms of the effect of corticosteroids in a patient with late septic shock. DesignCase report. SettingThe medical intensive care unit at University Medical Center Utrecht. PatientAn 86-yr-old female patient with late septic shock requiring mechanical ventilation and vasopressive agents. InterventionsAdministration of hydrocortisone, 300 mg daily. Measurements and Main Results Within 3 days of corticosteroid treatment, the patient could be weaned of vasopressive agents and mechanical ventilation. Serum C-reactive protein levels normalized. Nuclear factor-&kgr;B activation in unstimulated and in vitro lipopolysaccharide-stimulated peripheral blood mononuclear cells decreased to background level within 5 days. Repeated functional tests of the hypothalamic-pituitary-adrenal axis were normal. ConclusionOur data suggest that the pathophysiologic mechanism behind the clinical effects of supraphysiologic doses of corticosteroids in late septic shock is directly related to the inhibition of nuclear factor-&kgr;B in peripheral blood mononuclear cells.

Activation of Human Macrophages by Amyloid-β Is Attenuated by Astrocytes

In Alzheimer’s disease, neuritic amyloid-β plaques along with surrounding activated microglia and astrocytes are thought to play an important role in the inflammatory events leading to neurodegeneration. Studies have indicated that amyloid-β can be directly neurotoxic by activating these glial cells to produce oxygen radicals and proinflammatory cytokines. This report shows that, using primary human monocyte-derived macrophages as model cells for microglia, amyloid-β1–42 stimulate these macrophages to the production of superoxide anions and TNF-α. In contrast, astrocytes do not produce both inflammatory mediators when stimulated with amyloid-β1–42. In cocultures with astrocytes and amyloid-β1–42-stimulated macrophages, decreased levels of both superoxide anion and TNF-α were detected. These decreased levels of potential neurotoxins were due to binding of amyloid-β1–42 to astrocytes since FACScan analysis demonstrated binding of FITC-labeled amyloid-β1–42 to astrocytoma cells and pretreatment of astrocytes with amyloid-β1–16 prevented the decrease of superoxide anion in cocultures of human astrocytes and amyloid-β1–42-stimulated macrophages. To elucidate an intracellular pathway involved in TNF-α secretion, the activation state of NF-κB was investigated in macrophages and astrocytoma cells after amyloid-β1–42 treatment. Interestingly, although activation of NF-κB could not be detected in amyloid-β-stimulated macrophages, it was readily detected in astrocytoma cells. These results not only demonstrate that amyloid-β stimulation of astrocytes and macrophages result in different intracellular pathway activation but also indicate that astrocytes attenuate the immune response of macrophages to amyloid-β1–42 by interfering with amyloid-β1–42 binding to macrophages.

Intracellular pathways involved in TNF-α and superoxide anion release by Aβ(1-42)-stimulated primary human macrophages

Abstract In this study, the intracellular signal transduction pathways leading to the production of TNF-α and superoxide anions by amyloid-β-stimulated primary human monocyte-derived macrophages was investigated. Using Western blotting and specific inhibitors it is shown that both ERK 1/2 and p38 MAPK signal transduction pathways as well as PKC are involved in the amyloid-β-stimulated superoxide anion production. In contrast, only ERK 1/2 MAPK seems to be involved in TNF-α production: questioning the connection between PKC and ERK 1/2 activation. Our results suggest the use of ERK 1/2 MAPK inhibitors in the prevention of macrophage activation in the context of Alzheimers disease.

The chemotherapeutic agent bleomycin in a two-drug combination with zidovudine, ritonavir or indinavir synergistically inhibits HIV Type-1 replication in peripheral blood lymphocytes

It has been suggested that the combination of cancer chemotherapy with antiviral therapy is helpful for the containment of lymphomas in HIV-infected patients. Since we have recently shown that the nucleic acid binding chemotherapeutic agent bleomycin in itself has antiviral properties, we looked to see if there was any possible synergy with current anti-HIV agents. Combinations of zidovudine, indinavir or ritonavir with bleomycin, synergistically inhibited HIV-1(AT) replication in stimulated peripheral blood lymphocytes (combination index at 50% virus inhibition was 0.427, 0.604 and 0.535, respectively) and this synergism was not accompanied by any synergistic effects on cytotoxicity. We conclude from these data that further studies to investigate the clinical efficacy of combinations of antiviral and cancer chemotherapeutic agents are warranted in relation to viral load improvement.

The influence of antibiotic prophylaxis on bacterial resistance in urinary tract infections in children with spina bifida

BackgroundBacterial resistance to antibiotics is an increasingly threatening consequence of antimicrobial exposure for many decades now. In urinary tract infections (UTIs), antibiotic prophylaxis (AP) increases bacterial resistance. We studied the resistance patterns of positive urinary cultures in spina bifida children on clean intermittent catheterization, both continuing and stopping AP.MethodsIn a cohort of 176 spina bifida patients, 88 continued and 88 stopped using AP. During 18 months, a fortnightly catheterized urine sample for bacterial pathogens was cultured. UTIs and significant bacteriuria (SBU) were defined as a positive culture with a single species of bacteria, respectively with and without clinical symptoms and leukocyturia. We compared the percentage of resistance to commonly used antibiotics in the isolated bacteria in both groups.ResultsIn a total of 4917 cultures, 713 (14.5%) had a positive monoculture, 54.3% of which were Escherichia coli. In the group stopping AP, the resistance percentage to antibiotics in UTI / SBU bacteria was lower than in the group remaining on AP, even when excluding the administered prophylaxis.ConclusionStopping antibiotic prophylaxis for urinary tract infections is associated with reduced bacterial resistance to antibiotics in children with spina bifida.Trial registrationISRCTN ISRCTN56278131. Registered 20 December 2005.

Combining iron chelators with the nucleoside analog didanosine in anti-HIV therapy.

Iron chelation which would make iron un-available for redox reactions could influence HIVreplication in two possible ways: first, by inacti-vation of the iron-dependent cellular enzyme ri-bonucleotide reductase (RR) which is responsiblefor generating the building blocks for viral DNA.Deferoxamine (DF) was indeed shown to reducedATP and dGTP pools by ˇ95% [1]. A secondmechanism would be via reduction of nuclearfactor-jB (NF-jB) activation [2].The purpose of this study was to employ theanti-proliferative e•ects of the hexadentate ironchelator, DF and the recently registered orallyactive bidentate, deferiprone (L1) in antiviralcombinations with the adenosine analog didano-sine (ddI). Stimulated, infected peripheral bloodlymphocytes (PBL) were incubated with DF or L1alone, ddI alone or a combination of the two.Multiply diluted fixed-ratio combinations of thedrugs were used and samples taken for the mea-surement of the HIV core antigen, p24, 5 daysafter compound addition. The IC

Cutaneotrichosporon (Cryptococcus) cyanovorans, a basidiomycetous yeast, isolated from the airways of cystic fibrosis patients

Cystic fibrosis (CF) patients are colonized with a multitude of bacteria and fungi. From respiratory samples of two CF patients in our institute, a difficult to identify yeast was isolated repeatedly. This yeast was eventually identified as Cutaneotrichosporon (Cryptococcus) cyanovorans by internal transcribed spacer (ITS) and ribosomal large subunit (LSU) sequencing. C. cyanovorans is a basidiomycetous yeast originally reported as environmental isolate from South African soil and has not been described before as clinical isolate from CF patients.

The effect of deoxynucleosides on cell proliferation of peripheral blood lymphocytes treated with deferoxamine or hydroxyurea

peripheral blood lymphocytes treated with deferoxamine or hydroxyurea Tjomme van der Bruggen , Niki A. Georgiou , Maroeska Oudshoorn , Hans S.L.M. Nottet , Joannes J.M. Marx , B. Sweder van Asbeck b,* a Eijkman-Winkler Institute for Microbiology, Infectious Diseases and In ammation, Utrecht, The Netherlands b Department of Internal Medicine, University Medical Center Utrecht, P.O. Box 85500, F 02.126, 3508 GA Utrecht, The Netherlands